I. A group of 838 patients in the private practice of a psychiatrist on the Pacific Coast is found to come from homes above the average of the state's population in socio-economic status, and much above the average of the patients sterilized in California state hospitals for mental disease.2. This is selective and is not to be explained as showing that mental diseases occur more frequently in the intellectually superior part of the population.3. The private patients are rather younger than an institutional population, and are at ages when marriage and childbirth are likely.4. Significant differences of age and marriage rate are found between patients with various types of mental diseases.5. Women outnumber men two to one in the classification of manic-depressive psychoses, but this is not believed to represent a genetic difference in the etiology of the disease.6. When age is taken into account the private patients are found to have a high marriage rate.7. The divorce rate is much higher in patients with mental disease than it is in the population as a whole.8. The divorcees apparently constitute a particularly unstable group which marries early and divorces soon after marriage.9. There is in this group no tendency for men of higher socioeconomic status to marry at later ages.10. Those who marry late are about as likely to have large families as those who marry early. This points to the widespread use of contraceptive measures in this group, at least among those who marry early.II. The number of living children in the completed family of either male or female patients is three. This is enough to perpetuate the group, and is higher than the size of family in most groups of American college graduates.12. The relation between size of family and socio-economic status of parents is about the same in this group as in normal groups and other abnormal groups that have been studied.13. Although dementia præcox patients have a diminished marriageability, the fecundity of those who do marry is relatively high.14. It is concluded that the existence of a degree of mental disease serious enough to cause the individual to consult a psychiatrist has not tended to reduce the frequency of marriage or the size of family, as compared with the non-psychopathic population of similar age and socio-economic status.15. If marriage and parenthood are less desirable among psychopaths than in the healthier part of the population, it is evident that further steps, voluntary or compulsory, are required among psychopaths.